Recent Marijuana Use and Associations With Exhaled Nitric Oxide and Pulmonary Function in Adults in the United States

Abstract

The medical and recreational use of marijuana is now legal in some parts of the United States; the health effects are unknown. We aimed to evaluate associations between recent marijuana use and exhaled nitric oxide (eNO) and pulmonary function. We performed a cross-sectional study of 10,327 US adults participating in the National Health and Nutrition Examination Survey in the years 2007 to 2012. We examined associations between marijuana use and eNO, FEV1, FVC, the FEV1/FVC ratio, and forced expiratory flow (midexpiratory phase) (FEF25%-75%) by weighted linear regression. In the study population, there were 4,797 never users, 4,084 past marijuana users, 555 participants who used marijuana 5 to 30days before the examination, and 891 participants who used marijuana 0 to 4days before the examination. Current marijuana use in the past 4days was associated with 13%lower eNO (95%CI, -18%to 8%). FVC was higher in past users (75mL; 95%CI, 38-112) and current users in the past 5 to 30days (159mL; 95%CI, 80-237) and in users within 0 to 4days of the examination (204mL; 95%CI, 139-270) compared with never users. All associations remained unchanged and statistically significant in sensitivity analyses excluding current and past tobacco users. Current marijuana use was associated with lower levels of eNO and higher FVC. The lower eNO in marijuana smokers suggests that short-term exposure to marijuana may, like tobacco, acutely affect the pulmonary vascular endothelium and impair airflow through the small airways.